SUBSIM: The Web's #1 resource for all submarine & naval simulations since 1997 
072613, 01:41 PM  #1 
Count Dracula

[TEC] Real navigation Tutorials
in this thread i will try to show u how to fix your position on the map without using the navigator From the game with TDW's UI and MagUI when DrJones will release the new version of the MagUI.
The math and others calculation are same with both UI's but there are difrent sextant. Remember we don't have a real sextant to calculate the sextant index error and make some other correction so we can be 100% accurate First Tutorial: Finding The Latitude 1. Noon Latitude "Local Noon" is the exact time when the Sun reaches its highest point in the sky. This is also the time that it crosses the vertical, imaginary line, that astronomers call the "meridian". This is a very simple method enabling the observer to determine latitude by measuring the maximum altitude of the sun (or any other object). No accurate time measurement is required. The altitude of the sun passes through a flat maximum approximately(see noon longitude) at the moment of upper meridian passage (local apparent noon, LAN) when the GP of the sun has the same longitude as the observer and is either north or south of him, depending on the declination of the sun and observer’s geographic latitude. The observer’s latitude is easily calculated by forming the algebraic sum or difference of the declination and observed zenith distance z (90°Ho) of the sun, depending on whether the sun is north or south of the observer. now let's see this in game all what wee need is the alamanac from 1939  1945 an online almanac can be found here Click to measure the sun angle click on the navigator the sextant and u will see the screen after that click on Enable Sextant and align the te sextant to the water line ( horizont ) now search for the sun and measure the angle of the sun as we see we have the sun at 42.54 degree no let's do some math to find the latitude first we need to find Zenith Distance = 90  42.54 we convert the 90 degree to 89.60  42.54 = 47.06 is the Zenith Distance now let's see the sun declination at 1939. sept. 01 12:00 PM Sun declination is N 8. 31 so now let's see we are in the same hemisphere ( N ) but the sun is belove us so we apply the Latitude = Zenith Distance + Declination Latitude = 47.06 + 8.31 Latitude = 55.37 now let's what the navigator say about our latitude whoop 55.37 N pretty nice ha ? if u find your latitude then u can find your way home or your destination at sea when DrJones will finis the MagUI new version i will show u also with that UI mod. PS. if somebody have an 1939  1945 .PDF almanac and can share it with use i really apreciate it thx.
__________________
Last edited by Sjizzle; 050114 at 04:46 AM. 
072613, 01:42 PM  #2 
Count Dracula

Second Tutorial
Mark our position on the map and find the Longitude Remember we don't have a real sextant to calculate the sextant index error and make some other correction so we can be 100% accurate Let's start with measuring the sun angle Now we do the math to find the Lat. Zenith distance = 89.6 – 42.51 = 47.09 Lat. = Zenith Distance + Declination Lat. = 47.09 + 8.31 = 55.40N u can download this spreadsheet from here Download Each degree on the game map is 120 km. Now let’s see how to market on the map without the navigator help Each degree on the game map is 120 km. We do again some math 120 : 60 = 2km We know that assumed Lat. is 55 but how we find that 40 simple 40 x 2 = 80km ( when u draw from the bottom to the top u multiply and when u draw it from the top to the bottom u divide ) Let’s draw that 80 km on the map. Now let’s find the Long Open that excel work sheet and look at GHA there is 259.57 and to LHA where is 20.00 359.57 – 20 = 339.57 – 360 = 20.43 Long = 20.43E We know that we are at Long. 20E now 43:2 = 26.5km let’s draw it on the map ( When u draw it from the west to east left side to right side u multiply and when u draw it from east to the west right to the left u divide) Now let’s see what the navigator say as u see the navigator calculation is Lat. 55.41N and Long. 20.47E so we are not far as i said we can’t be 100% accurate cos we don’t know the sextant index error and dip and other correction this can be my error or the game error so we can not chek where is the uboat to see wich one is correct but i think that is pretty good and give more realism to the game. I think that the navigator can be removed from the game if somebody wanna play hardcore and mark his position on the Map :P on bad weather and fogy day u are really lost at the sea if u play hardcore.
__________________
Last edited by Sjizzle; 050514 at 05:09 PM. 
072613, 01:44 PM  #3 
Count Dracula

Reserved 2
__________________

072613, 01:44 PM  #4 
Count Dracula

Reserved 3
__________________

072613, 02:40 PM  #5 
Navy Seal
Join Date: Jan 2011
Location: CJ8937
Posts: 8,207
Downloads: 792
Uploads: 10

Thanks Sjizzle
By the way, I have just found this: http://www.allaboutsailing.co.uk/nav...ositionfixing P.S: if you need for more reserved posts, I will happily delete this one 
072613, 02:48 PM  #6 
Count Dracula

thanks gap
no need to delete now i am working on celestila fix position wich is a bit complicated .... wich one need some math knowledge Edit: HO. 229 book A very accurate method. It is produced in a six volume series. This course uses volume 3. The tables are used with the Nautical Almanac to obtain elements necessary to obtain position at sea. It is a straight forward method and requires no mathematical calculation beyond addition and subtraction of degrees and minutes and decimals of minutes. A popular method. idk if they have it in WW II
__________________

072613, 03:03 PM  #7 
Ocean Warrior

I'm sure they had it.. they had it since 1767 AD..
look here  http://en.wikipedia.org/wiki/Nautical_almanac Thanks for this great work.. I think it's time to me to learn it finally ..
__________________
. Where does human stupidity end? . El sueño de la razón produce monstruos ©  and for some people awakening will be cruel 
072613, 03:21 PM  #8 
Count Dracula

136 pages only with tables
__________________

072613, 03:31 PM  #9 
Navy Seal
Join Date: Jan 2011
Location: CJ8937
Posts: 8,207
Downloads: 792
Uploads: 10

I am afraid not
According to the following link, the particular nautical almanac that you are talking about was published sometime between 60's and 80's: http://fer3.com/arc/m2.aspx/HO22924...ar2011g15994 
072613, 04:21 PM  #10 
Navy Seal
Join Date: Jan 2011
Location: CJ8937
Posts: 8,207
Downloads: 792
Uploads: 10

Some useful navigation resources:
http://www.offshoreblue.com/navigation/ P.S: most of the documents are in pdf format. If only we could open them in game... Unfortunately I think this topic has been commented by TDW already, and IIRC it is not possible 
072613, 05:02 PM  #11 
Navy Seal
Join Date: Jan 2011
Location: CJ8937
Posts: 8,207
Downloads: 792
Uploads: 10

How a Sextant Works
an informative short article about the workings of a sextant
http://www.tecepe.com.br/scripts/AlmanacPagesISAPI.dll Sorry for hijacking the thread 
072713, 12:33 PM  #12 
Lieutenant
Join Date: Jan 2012
Posts: 252
Downloads: 66
Uploads: 0

Running fix needs also known time from 1st LOP to 2. LOP, steady course and steady speed to calculate your traveled distance and direction between 1. LOP and 2. LOP.
__________________
Robert Schmidt, LTJG U43 
072713, 12:51 PM  #13  
Navy Seal
Join Date: Jan 2011
Location: CJ8937
Posts: 8,207
Downloads: 792
Uploads: 10

Quote:
Quote:


073013, 02:01 PM  #14 
Count Dracula

this is a good one
http://navsoft.com/Celestial_Navigation_Tutorial.pdf
__________________

073013, 02:03 PM  #15  
Count Dracula

Quote:
A fix is called a running fix when one or more of the LOPs used to obtain it is an LOP advanced or retrieved over time. In order to get a fix the LOP must cross at an angle, the closer to 90° the better. This means the observations must have different azimuths. During the day, if only the Sun is visible, it is possible to get an LOP from the observation but not a fix as another LOP is needed. What may be done is take a first sight which yields one LOP and, some hours later, when the Sun's azimuth has changed substantially, take a second sight which yields a second LOP. Knowing the distance and course sailed in the interval, the first LOP can be advanced to its new position and the intersection with the second LOP yields a running fix.
__________________


Thread Tools  
Display Modes  

